FEATURE: Use second factor for admin confirmation (#14293)

Administrators can use second factor to confirm granting admin access
without using email. The old method of confirmation via email is still
used as a fallback when second factor is unavailable.

app/assets/javascripts/admin/addon/models/admin-user.js

@@ -99,9 +99,20 @@ const AdminUser = User.extend({
     });
   },
 
-  grantAdmin() {
+  grantAdmin(data) {
     return ajax(`/admin/users/${this.id}/grant_admin`, {
       type: "PUT",
+      data,
+    }).then((resp) => {
+      if (resp.success && !resp.email_confirmation_required) {
+        this.setProperties({
+          admin: true,
+          can_grant_admin: false,
+          can_revoke_admin: true,
+        });
+      }
+
+      return resp;
     });
   },